Aerial platform{41 s safety control

ABSTRACT

A hydraulic flow control circuit for use with the hydraulic lifting piston in an aerial platform for controlling the rate of the descent of the aerial platform when the power supply for furnishing fluid pressure to the lifting piston is inoperative including a flow conduit for flowing hydraulic fluid from the high pressure side of the lift piston with orifice means in such flow line for restricting the rate of fluid flow to limit the rate of descent of the aerial platform with flow control means adjacent the aerial platform to enable the occupant of the aerial platform to lower the platform safely when the power power source for hydraulic fluid is inoperative.

United States Patent Visinsky AERIAL PLATFORM-S SAFETY CONTROL 992,436 5/1911 March et al. 2 s1/11s Primary Examiner-Reinaldo P. Machado Attorney-Pravel et a1.

[57] ABSTRACT A hydraulic flow control circuit for use with the hydraulic lifting piston in an aerial platform for controlling the rate of the descent of the aerial platform when the power supply for furnishing fluid pressure to the lifting piston is inoperative including a flow conduit for flowing hydraulic fluid from the high pressure side of the lift piston with orifice means in such flow line for restricting the rate of fluid flow to limit the rate of descent of the aerial platform with flow control means ad-- jacent the aerial platform to enable the occupant of the aerial platform to lower the platform safely when the power power source for hydraulic fluid is inoperative.

2 Claims, 2 Drawing Figures [76] Inventor: Walter L. Vlslnsky, 302 Sidney,

Houston, Tex. 77003 [22] Filed: Aug. 16, 1971 [21] Appl. No.: 171,811

[52] US. Cl. 182/148, 182/2 [51] Int. Cl B661 11/04 [58] Field of Search 182/2, 19, 141, 148; 60/52 HE; 251/118 [56] References Cited UNITED STATES PATENTS 2,151,057 3/1939 Suth 60/52 HE 2,059,255 11/1936 Lassiat'. 251/118 3,498,411 3/1970 Worden 182/2 2,288,297 6/1942 Najman 251/118 849,406 4/1907 Longfellow 251/118 AERIAL PLATFORM-S SAFETY CONTROL BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to safety control apparatus which enables the occupant of an aerial platform to control its descent when the hydraulic power supply system is inoperative.

2. Background of the Invention Aerial platforms are used extensively in industry for positioning workers at elevated positions for performing various tasks such as painting, routine maintenance and repair as well as construction, and the like. The hydraulic aerial platforms heretofore available have included a means for automatically locking the boom cylinders in position in the event of hydraulic or power failure while the unit is being operated. However, such prior art aerial platform do not include a means for permitting the occupant of the aerial platform to lower the platform or basket in the event of such hydraulic power failure. As a result, many workers have been injured in attempting to extracate themselves from an aerial platform which is locked in an elevated position.

SUMMARY The present invention comprises a new and improved aerial platform safety control circuit which enables the occupant of an aerial platform to actuate a hydraulic system for safely lowering an elevated basket or platform after it has been locked in an elevated position by an automatic safety valve arrangement which locks the boom in the event of a hydraulic or power failure. The apparatus the present invention includes is a nipple orifice of a preselected size which is positioned in a hydraulic flow control line for communicating hydraulic fluid from the high pressure side of the actuating piston to a return line for returning such fluid to thesump of the main hydraulic system.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view showing an aerial platform with the boom in a raised position for supporting a worker at an elevated position above the ground;

FIG. 2 is a sectional view of a flow control orifice used in the safety control circuit of the present inven tion for lowering the boom when locked in a raised position.

DESCRIPTION OF THE PREFERRED EMBODIMENT Briefly, the apparatus of the present invention, designated generally A in FIG. 1 of the drawings, is shown mounted on a boom B of an aerial platform designated generally P, which is carried on a truck or movable base C. Such boom B has a basket or aerial platform D mounted at the free end thereof for supporting one or more workers for doing overhead jobs in elevated positions at heights up to fifty feet above the ground level. With most hydraulic aerial platforms in use today there is provided an automatic safety apparatus which automatically locks the boom B in position in the event of a failure of either the hydraulic control system or the power system which actuates the hydraulic control system. In the event the boom B is in an extended position as shown in FIG. 1 of the drawings, the occupant of the aerial platform or basket D is stranded in an elevated position which, in some instances, is several feet above the ground. The apparatus A of the present invention provides a safe and dependable means for lowering the upper boom arm to which the platform D is connected even through the hydraulic system has failed or, the power system which actuates the hydraulic system has failed.

The boom B includes a lower beam 1 1 which is pivotally mounted on the truck C and an upper beam 12 which is pivotally connected at 13 to the upper end of the lower arm 11. The aerial platform or basket D is pivotally mounted at the free end of the upper beam 12. As shown, a hydraulic piston 14 is provided for raising or pivoting the lower beam 1 1 upwardly from a substantial horizontal position to a substantially vertical position and similarly, a hydraulic piston 15 is provided for pivoting the upper beam 12 from a lower to an upper position. Generally, the upper beam swings or pivots through an arc of approximately 180 whereas the lower beam 11 pivots upwardly only approximately The hydraulic cylinders 14 and 15 are normally double acting and include pistons which are actuated by a hydraulic fluid supply source (not shown) mounted on the' truck C. Such hydraulic system is operatively connected to the cylinders 14 and 15 for actuating pistons (not shown) to move their respective connecting rods 14a and 15a for raising and lowering the booms 11 and 12, respectively. Pilot operated check valves are normally associated with each of the cylinders 14 and 15 for automatically locking the booms in position in the event of hydraulic or power failure while a unit is being operated. A control valve or check valve 20 is provided at the base of the upper cylinder 15 for controlling the flow of fluid from the high pressure cylinder 15.

The orifice nipple 30 is connected to the cylinder 15 by means of a T with the control valve 20 connected to the other branch of the T. A conduit 31 connects the nipple orifice 30 at the lower end of the hydraulic cylinder 15 with the inlet of a control mechanism 32 positioned adjacent the aerial platform or basket D where it may be reached and manually operated by an occupant of such basket or aerial platform. In the preferred form. of this invention the discharge of valve 32 is connected to the return line 39 which is a part of the fluid return manifold in the standard hydraulic power actuating and control found on hydraulically operated aerial platforms. Altemately, a separate return flow line (not shown) extends back to the hydraulic sump (not shown) for flowing hydraulic fluid directly into such sump of the hydraulic system. The orifice member 30 is positioned in the flow control line to restrict the flow of hydraulic fluid through such line and thereby control the rate of descent of the aerial platform or basket D and the upper boom 12 on which is carried. It will be appreciated that by opening the valve" 32 in the flow line 31 in which the orifice nipple 30 is connected, hydraulic fluid will pass from the high pressure side of the piston in the hydraulic cylinder 15 through the low pressure return manifold 39 to the sump, By opening flow of hydraulic fluid through the safety line 31 the weight of the boom 12, the basket D with the occupant therein will cause the piston to be moved downwardly in the hydraulic cylinder 15 and thereby lower the aerial platform D to a point of safety. By allowing hydraulic fluid which has accumulated beneath the piston in the cylinder 15 to escape or bleed off through the orifice nipple, the piston will thereby move downwardly to lower the boom 12. The rate of outflow of such hydrau-j lic fluid from the piston cylinder however is controller by the orifice restriction 37 in the orifice nipple '30 someone at ground level by opening the valves 32 or 53, respectively, to allow hydraulic fluid uto flow from shown in detail in FIG. 2 of the drawings. As shown, the

orifice nipple is provided with the threaded inlet and discharge passages 30a and 30b, respectively. A restriction or small diameter conduit 37 is provided between the inlet and discharge passages 30a and 30b for limiting the flow of hydraulic therethrough, so that when the valve 32 is opened, fluid flowing from the hydraulic cyl inder 15 through the conduit or line 31 and hence throughthe return manifold.- Conduit 39 to the sump the high pressure to the lowpressure sideofthe piston in the cylinder 15 to thus lower the boom 12 and the platform D. j i

' It will be appreciated that the safety control apparatus of the present invention can also be used for lowering the lower bomb or arm 11 by providing a hydraulic circuitwith a separate control at the platform D. g l

It will further understood that the orifice nipple 30 alone willserve as a safety control'should the line 31 will be restricted sufficiently to permit the weight of the I boom 12, the platform D with one or moreoccupants' therein to cause the boom 12 to descent to lower the basket D safely-and without injury or damage to the platform or its occupants.

Also, in the preferred from of this invention, a second or auxiliary control arrangement is provided for operating the safety control apparatus of the present invention froma location which'is remote to the aerial plat-' form D, such as at the base of the lower boom member I to the sump to thereby lower the aerial platform D.

Thus, it will be appreciated that with the alternate apparatus of the present invention, hydraulic fluid may be transferred or withdrawn from the high pressure side of the piston in the cylinder 15 through a rate of flow control orifice to thus limit the rate of descent of such aerial platform D. By providing this remote means for lowering the platform D, a worker on the ground can actuate the safety control device so as to safely lower the aerial platform D in the event the occupant thereof should be injured or unaware of the safety control apparatus or unable to actuate it for any reason.

Thus, with the apparatus of this invention an aerial platform which has been'locked in an extended or elevated position due to failure either of the hydraulic sys- V tem or of the hydraulic power system can be lowered I safely by the occupant in the aerial platform or by to the valve 32"be broken the orifice 30 will nevertheless control the flow of fluid out of the cylinder 15 so i as to retard the rate of descent of the boom 12 and form Dto asafe rate. M

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials as well plat- I asin the details of the illustrated construction may be 7 made without departing from the spirit of the invention.

I claim: a V

1. In an aerial platform actuated by a hydraulic system having a hydraulic fluid power supply and a return 7 circuits operably connected to a hydraulic cylinder having a piston connected to a boom for raising and lowering an aerial platform and havingm'eans for locking the piston in position when the hydraulic power supply systembecomes inoperative, the improvement 4 comprising:

a. conduit means operably connecting said hydraulic i 'cylinderbelow said piston and communicating said return circuit; b. valverneans in said conduitmeans adjacent said aerial platform at the end of said boom forrmanual operation'by an occupant of said platform to flow hydraulic fluid from said cylinder to said return cir platform concuit to lower said boomand aerial nee ted thereon; and g I c. orifice means in said conduit means for restricting the flow of hydraulic fluid therethrough to control n the rate of descent of said aerial platform.

2. The invention of claim one wherein said conduit 7 5 means is connectedto the hydraulic fluid return circuit at the manifold adjacent said aerial platform atthe-e'nd 'of the boom. 2 

1. In an aerial platform actuated by a hydraulic system having a hydraulic fluid power supply and a return circuits operably connected to a hydraulic cylinder having a piston connected to a boom for raising and lowering an aerial platform and having means for locking the piston in position when the hydraulic power supply system becomes inoperative, the improvement comprising: a. conduit means operably connecting said hydraulic cylinder below said piston and cOmmunicating said return circuit; b. valve means in said conduit means adjacent said aerial platform at the end of said boom for manual operation by an occupant of said platform to flow hydraulic fluid from said cylinder to said return circuit to lower said boom and aerial platform connected thereon; and c. orifice means in said conduit means for restricting the flow of hydraulic fluid therethrough to control the rate of descent of said aerial platform.
 2. The invention of claim one wherein said conduit means is connected to the hydraulic fluid return circuit at the manifold adjacent said aerial platform at the end of the boom. 